The present invention relates to clamps or clips for hoses, pipes or like structures. More particularly, the invention relates to clamps or clips (hereinafter called clips or hose clips) of the type wherein a housing receives the end portions of a band which is trained or looped around a hose or a like structure. The housing rotatably supports a tensioning element in the form of a screw having a shank whose thread mates with the thread on one end portion of the band. The head of the screw is adjacent to one axial end of a tubular section forming part of or constituting the housing. Still more particularly, the invention relates to improvements in hose clips of the type having means for holding one end portion of the tubular section against radial movement relative to the shank and such holding means extends in the axial direction of the screw.
It is already known to provide a hose clip with a tensioning screw (hereinafter called screw for short) whose head has a cylindrical, conical or polygonal outline. The head and the shank of the screw define a shoulder which abuts against one end face of the tubular section of the housing wherein the shank rotates. As a rule, the tubular section of the housing resembles a tunnel including a substantially semicylindrical part which is remote from the end portions of the band and surrounds one half of the externally threaded shank, and a substantially U-shaped part which confines the two overlapping end portions of the band, so that the externally threaded end portion of the band can mate with the thread on the shank. Parts of end portions of the tubular section are recessed in order to allow for convenient insertion of the end portions of the band. The recesses are normally provided in the U-shaped part of the tubular section, i.e., the U-shaped part is shorter than the semicylindrical part as a result of the provision of recesses in the end portions of the tubular section. That end portion of the band which is not provided with external threads is adjacent to a normally flat or substantially flat bottom wall of the tubular section, and the threaded end portion of the band extends between the unthreaded end portion of the band and the shank of the tensioning screw. When the screw is rotated in a direction to tension the band, i.e., to increase the tensional stress upon the looped median portion of the band by way of the threaded end portion, the force which the thread of the shank transmits to the band acts in substantial parallelism with the axis of the shank and such force is applied in the region of those portions of threads on the threaded end portion of the band and on the shank which are in mesh with each other. The just mentioned force tends to pivot the screw about an axis which is normal to the central symmetry plane of the band and includes the axis of the shank. In other words, the screw tends to pivot about the axis of a hose or an analogous structure which is surrounded by the looped median portion of the band while the latter is subjected to a gradually increasing tensional stress as a result of clockwise rotation of the shank with reference to the tubular section of the housing. The just mentioned pivoting of the screw results in a movement of the head of the screw closer to the bottom wall of the housing while the free end or tip of the shank approaches the topmost portion of the tubular section, namely, that portion of the semicylindrical part of the tubular section which is remotest from the bottom wall. Owing to the provision of recesses at the ends of the U-shaped part of the tubular section, the head of the screw cannot contact and bear against the bottom wall and, as a result of such absence of contact, the head is likely to penetrate into the respective end portion of the tubular section of the housing whereby the tubular section expands or bursts open to terminate the engagement between the shank and the threaded end portion of the band. This can result in spillage of the fluid which is conveyed in a hose, pipe or nipple, and the thus damaged or destroyed clip must be replaced with a fresh clip.
Proposals to reduce the likelihood of expansion of the housing for a tensioning screw which is used in a hose clip are disclosed in British Pat. No. 664,855 to Jamie and in French Pat. No. 933,013 to Robinson. The patented hose clips employ screws with cylindrical heads and such hose clips further comprise inserts which are made of sheet metal and have circular openings for the shanks of the screws. The inserts are mounted on the housing, and their openings are immediately adjacent to the heads of the respective screws. Each insert has a cylindrical portion which surrounds a part of the respective end portion of the housing. The cylindrical portion is not a complete cylinder because it is interrupted at that side which is adjacent to the bottom wall, i.e., in the proximity of the two overlapping end portions of the band. In fact, the underside of the cylindrical portion of the insert is parallel to the adjacent exposed side of one (threaded) end portion of the band so that the latter can be readily threaded through the housing. Those parts of the cylindrical portion of the insert which are adjacent to the bottom wall of the housing are parallel to each other and are outwardly adjacent to two flat side walls of the housing.
The just described patented hose clips are less likely to permit tilting of the screw with reference to the end portions of the band, i.e., they are less likely to permit a pivotal or orbital movement of the screw about the axis of the structure which is surrounded by the looped median portion of the band. However, the rotating screw transmits to the insert a substantial torque which tends to rotate the insert in a clockwise direction (if the thread on the shank of the screw is a right-hand thread). Such torque is generated in part as a result of frictional engagement between the surface surrounding the opening in the insert and the external surface of the shank, and in part as a result of engagement between the thread of the shank and the thread on one end portion of the band. The torque is opposed by the side walls of the housing; however, such opposition is relatively small because the side walls are likely to undergo deformation as soon as the tensional stress upon the band reaches a relatively low threshold value. The cylindrical portion of the insert is separated from the housing in response to deformation of the side walls so that the insert is incapable of preventing a pivotal or tilting movement of the screw and the attendant additional deformation or total destruction of the housing. Moreover, in order to furnish a reasonable resistance to deformation and to adequately support the part-cylindrical portion of the insert, the side walls of the housing which is disclosed by the British or French patent must be relatively long. This, in turn, necessitates the provision of a relatively long bottom wall so that the threading of the externally threaded end portion of the band through the housing presents serious problems. Moreover, a relatively long bottom wall cannot adequately conform to the curvature of the structure which is surrounded by the band, especially if such curvature is not constant, i.e., if one and the same type of clip is to be used in connection with hoses or analogous structures having relatively large or relatively small diameters. If the curvature of the bottom wall of the housing deviates from the curvature of the adjacent portion of the structure within the looped median portion of the band, the distribution of tensional stresses upon longitudinally spaced portions of the band is not uniform which can cause leakage between a hose and a part which is surrounded by the hose within the confines of the looped median portion of the band. The likelihood of leakage is especially pronounced if the fluid which is to flow through the hose is maintained at a relatively high pressure.
Shortening of the bottom wall by removing its end portions (as considered in the circumferential direction of the looped median portion of the band) is not desirable in or is plainly detrimental to the patented hose clip (e.g., under the aforementioned circumstances), even though a shorter bottom wall could more readily conform to the outline of the structure within the confines of the looped median portion of the band. If the bottom wall of the housing is relatively short, the housing is more likely to be tilted in response to rotation of the screw in a direction to tension the band whereby the lower part of one side wall of the housing strikes against the band. In the absence of such contact with the band, the housing would be likely to change its orientation with reference to the screw in such a way that its tubular section would not be coaxial with the shank. Also, the aforementioned shoulder between the shank and the head of the screw would become disengaged from the adjacent end portion of the housing. Tilting or a similar undesirable change of orientation of the housing with reference to the screw is especially likely to occur if the cutout in the cylindrical portion of the aforementioned insert which is used in the patented hose clips is remote from the bottom wall of the housing. When the lower end of a side wall of the housing strikes against the band, the threaded end portion of the band cannot be readily moved lengthwise because the housing is likely to engage the thread of the band and to oppose rotation of the screw in a direction to increase the tensional stress upon the band. Undesirable engagement between the housing and the thread on the band is particularly likely to occur when the housing consists of sheet metal and the thread on the band is formed by stamping, forging or a similar procedure. The edge faces of the metallic housing will penetrate into the grooves, slots or analogous depressions or apertures between the portions of the thus formed thread on the band.